Page:Popular Science Monthly Volume 9.djvu/741

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in these animals. It is often connected anteriorly with a median frontal ganglion (Fig. 7, E), lying anterior to and below the brain, which supplies branches to the mouth and adjacent parts. This oral or frontal ganglion, besides being connected with the brain, also gives origin to a median recurrent nerve (e). This nerve is connected with other branches, proceeding from one or two pairs of lateral ganglia (c), near to, and taking origin from, the œsophageal cords. The system of nerves thus derived furnishes branches to the stomach, the intestines, and other viscera. In addition, we meet in insects with another well-developed set of visceral nerves, taking origin from a chain of minute ganglia, which lie upon and are connected with the large ventral ganglionated cord. These nerves are distributed to the extensive and greatly multiplied air-tubes, or respiratory organs. They are known to anatomists as "uervi transversi," and are much more developed in insects than are its representatives among any other class of arthropods.



AMONG the various branches of natural science which have in recent times attained a high development, geography holds a prominent rank. By this, however, we must understand, not so much that vast regions of previously unexplored country have been made known to the educated world; that rivers, seas, and mountains, have been discovered, and the courses of known streams more accurately defined in maps; but rather that geotectonic[2] data, of which a rich store has been collected, have been studied from broad and general points of view, and the individual phenomena ranged in the order of cause and effect. In earlier times geography was simply a catalogue of facts, and the earth's surface an ultimate datum; but nowadays we are beginning to regard the superficies of our planet as a result, to investigate the relations between its separate parts, and to note the changes which occur in it. In the words of Karl Patter: "Scientific geography by no means regards our planet as a lifeless, dead aggregate of an unorganized nature, or, as Herodotus expresses it, a disk turned on a lathe; but as a truly and specially organized body in steady process of development, bearing within itself the life-germs of further evolution. Herein consists its unity; and it is in virtue of this, its living principle, that it is a whole, lending itself to an orderly presentation and development of its great system. Furthermore, it is this which makes of it a science instructive to the human mind—an indispensa-

  1. Translated from the German by J. Fitzgerald, A.M.
  2. Relating to the earth's structure.